In the end, President Obama won the coveted endorsement of New York City Mayor Michael Bloomberg. But it wasn't Obama's visits or entreaties that sealed it. It was Hurricane Sandy's.

Bloomberg endorsed Obama in an op-ed yesterday, arguing that Hurricane Sandy and other extreme weather events may not be directly caused by climate change, but that the risk that they are requires action by elected officials. Republican nominee Mitt Romney has backed off his previous pledges to act on climate change, Bloomberg said, making Obama the preferred choice.

"This issue is too important," he said. "We need determined leadership at the national level to move the nation and the world forward."

Both candidates have courted Bloomberg, hoping his image as a sensible centrist would bring them credibility with independent voters. In his column, Bloomberg critiqued positions of both candidates, but he concluded that the weight of Sandy -- and what he feared is a growing pattern of extreme weather events -- tipped the scale toward Obama.

Bloomberg pointed to the damage Sandy wrought on New York's subway and its grid, as well as the lives it has taken and business it has derailed. Like Hurricane Irene last year, he said, Sandy required a large-scale evacuation of neighborhoods.

"If this is a trend, it is simply not sustainable," he said.

But in an election that has focused almost exclusively on the economy, will the endorsement sway voters?

Bad timing for Romney? Steve Cohen, executive director of the Earth Institute and a sustainability professor at Columbia University, said the timing will work against Romney, who had shown some momentum in the polls. With the election just days away, the public is paying attention to visceral scenes of disaster and images of the president working hand-in-glove with Republicans like New Jersey Gov. Chris Christie.

"[Romney] needed to be the center of attention," Cohen said. "From Obama's perspective, the Bloomberg endorsement could not have been better timed."

Also, given that it is a disaster, the focus is momentarily off of the small-government discussion, Cohen said. To address the crisis, Bloomberg, Christie and other leaders have worked closely with firefighters, police departments and other publicly funded offices.

But Marc Morano, publisher of the climate skeptic blog Climate Depot, accused Bloomberg of betraying those harmed by Sandy.

"Bloomberg is insulting every victim of Sandy by implying the federal government can legislate the behaviour of storms and weather," he said in an email.

A spokesman for Sen. James Inhofe (R-Okla.), Congress' leading critic of climate science, panned Bloomberg's endorsement, saying Obama has failed to advance climate policy and has run the "global warming alarmist" movement into the ground.

"In fact, President Obama hardly even talks about global warming as he runs for reelection. Rather, he has been talking about his new found love of fossil fuels," spokesman Matt Dempsey said by email.

Bloomberg preferred earlier versions of Romney
For his part, Bloomberg said he approves of Obama's record on climate. Obama has helped shut down old coal plants and has advanced fuel-economy regulations, the mayor said.

By comparison, he said, Romney has supported policies to fight climate change in the past, but he has now reversed his path. Bloomberg said he would have considered voting for the 1994 or 2003 versions of Romney.

The endorsement left some in the pundit sphere wondering about Bloomberg's larger strategy. In a treatise of seven tweets, Washington Post columnist Ezra Klein said Bloomberg is attempting to snatch climate change from the partisan war.

By critiquing Obama and praising Romney's former policies, Klein said, Bloomberg established his bona fides as a centrist. Then, speaking as a centrist, Bloomberg attempted to situate climate change as a nonpartisan issue that must be urgently dealt with.

"Bloomberg's not endorsing Obama so much as he's trying to reset the incentives on climate change. It's a huge play," Klein said.

Paul Bledsoe, a policy consultant and a former Clinton White House staffer, said that given Bloomberg's appeal to independents, Republicans may now feel pressure to change their stance on climate.

"Romney has performed flip-flops on climate change worthy of an Olympic gymnast," he said. "And it now appears [Republicans] either have to take a stand or pay a political price."